1. Field of the Invention
The present invention relates to enzymatic liquid detergent compositions comprising both lipolytic and proteolytic enzymes, wherein the storage stability of the lipolytic enzymes is improved by the inclusion in the composition of a particular enzyme-stabilizing system.
2. Description of the Related Art
Enzymatic liquid detergent compositions are well-known in the art. They mainly contain a proteolytic enzyme, or a mixture of a proteolytic enzyme and an amylolytic enzyme. One of the major problems which is encountered with such enzymatic liquid detergent compositions is that of ensuring a sufficient storage-stability of the enzymes in these compositions.
There have already been various proposals for the inclusion of a variety of special enzyme-stabilising systems in such enzymatic liquid detergent compositions. A number of these proposals are directed to the use of a combination of a polyol and a boron compound as an enzyme-stabilizing system. Thus, Canadian Pat. No. 1,092,036 (Hora et al.) discloses enzymatic liquid detergents comprising a proteolytic and/or an amylolytic enzyme and an enzyme stabilizing system containing a polyol such as 1,2-propanediol, ethyleneglycol, erythritan, glycerol, sorbitol, mannitol, glucose, fructose, lactose, and a boron compound such as boric acid, boric oxide borax, alkalimetal ortho-, meta- and pyroborates which is capable of reacting with the polyol. In U.S. Pat. No. 4,404,115 (Tai), the combination of an alkalimetal pentaborate, optionally with an alkalimetal sulphite and/or a polyol is described as an enzyme-stabilizing system in enzymatic liquid detergents comprising a protease and/or an amylase.
In Japanese patent application No. 72/35,192 (Nagase), laid open to public inspection on Nov. 24, 1972, the use of mixtures of a polyol such as sorbitol or glycerol and borax to stabilize proteolytic enzymes in liquid detergents is disclosed.
There are several references disclosing enzymatic liquid detergent compositions which include the combination of a polyol and a boron compound in an enzyme-stabilizing system, e.g. British Pat. No. 2,079,305 (Boskamp), European Pat. No. 80,223 (Boskamp) and U.S. Pat. No. 4,537,707 (Severson), wherein the enzyme is a proteolyotic and/or amylolytic enzyme.
In U.S. Pat. No. 4,465,619 (Boskamp) an enzymatic liquid detergent composition is described, which may contain proteases, amylases, cellulases or lipases, and an enzyme-stabilizing system comprising a mixture of a polyol and a boron compound. This composition may not contain more than about 2% by weight of the boron compound.
In European Patent Application No. 258,068 (NOVO) published on Mar. 2, 1988, a detergent lipase is described, which can be stabilized in an aqueous detergent composition by the inclusion therein of 1,2-propanediol, optionally together with a calcium salt. Sorbitol is stated to have only a slight stabilizing effect.
None of these prior proposals deal with enzyme-stabilizing systems to improve the stability of lipolytic enzymes in liquid detergent compositions which also include a proteolytic enzyme. It is therefore an object of the present invention to provide for an enzyme-stabilizing system which, when included in an enzymatic liquid detergent composition which includes both a lipase and a protease, would improve the storage stability of the lipase therein.